Press-mold for use in the manufacture of metallic bars from finely-divided metallic powders.



v K. GLADITZ. mass MOLD FOR USE IN THE MANUFACTURE OF METALLIC BARS PROM PINELY DIVIDED METALLIC POWDERS.

. APPLICATION FILED MAY 2a, 1913. 1 91,430. Patented Mar. 24, 1914.

KARL GLADIIZ, OF LONDON, ENGLAND.

PRIEES M OLD FOR USE IN THE MANUFACTURE OF METALLIC BARS FRQM FINELY- DIVIDED METALLIC POWDERS.

censee.

Specification of Letters Patent. Patented Ilium. 2d, 1914.

Application filed May 28, 1913. Serial No. 770,414.

Z2) all whom it may concern:

Be it known that I, KARL GLAmrz, residin at London, England, have invented certain new and useful Improvements in Press-Molds for Use in the Manufacture of Metallic Bars from Finely-Divided Metallic Powders; and I do hereby 'declare the following to be a full, clear, and exact description of the invent-ion, such as will enable others skilled in the art to which it appertains to make and use the same.

This invention relates to an improved press mold for use in the manufacture of metallic bars from finely divided metallic powders, and more particularly the manufacture of tungsten bars or rods which can be employed for the production of fine tungsten wires or filaments by the use of the drawing process. a

The object of the said invention is to provide an improved press for obtaining suc tress-fully and in a simple, quick, and economic manner, tungsten barslor rods of any desired dimensions which are absolutely homogeneous, perfectly metallic, and completely free from bubbles or cracks.

According to the present invention, use is made for the production of bars or rods, of a tungsten metallic powder, the smallest particles of which are of a flufiy character. The tlufi'y character of the particles of this powder is of great physical importance for the pressing of the bars or rods, the fluffyparticles clinging together and permitting a very dense and homogeneous bar to be obtained, at the comparatively small pressure of 30 to kilograms per square millimeter- Such a bar is completely free from cracks and owing to its homogeneity, also very rigid. The fluffy metallic particles are exceedingly elastic and a bar which has been pressed by hydraulic pressure tends to expand after the pressure has been removed, by so to say, springing back inall its three directions proportionally to the three dimensions oi the bar. If the pressure in the press form is removed in one direction only,

the springing back of the bar causes the formation of Strata like cracks, andthe bars are thereby rendered useless.

I have found that by using a press form which simultaneously and instantaneously releases the bar in all its three directions,

when the pressure has been removed so as to allow it to expand to its full extent upward, laterally, and more especially longitudmally, I can obtain perfectly crackless bars of great length.

The invent-ion is illustrated by way of example 1n the accompanying drawings in wh1ch;-

Figure 1 is a plan view of the improved press t'orm, Fig. 2 a cross section thereof, and Fig. 3 a longitudinal elevation of the pressing knife or plun er.

The lmproved press orm comprises a bed a tormed with a recess in which are placed a l nlng b of naturally hard steel, two lateral lining plates 0 and d, which rest upon the bottom plate I) and small end plates 0 and f, whlch space apart the plates 0 and d. and together with the plates 5. 0 and (i incl ose a space :1: wherein the fluffy powder is inserted. The plate (8 can be shifted toward the plate 0 by means of a wedge shaped lockmg device 9 which abuts against the plate (l on the one side and against the inclined surface 71- of the bed a on the other side, the two ends of the wedge shaped member being .formed with screw threaded pins engaging with nuts 2' and j, which abut against the washers 7c and Z, and by means of which the wedge shaped member 7 can be shifted longitudinally, thereby increasing or decreasing the pressure-upon the plate '03.

The improved press form is used as follows :All the parts being in their position, the wedge shaped member 9 is moved in the direction of the arrow m by tightening the nut 2', whereby the plate (l is pressed against the end plates e and f, and the latter are thus fixed in their position. The fiufiy powder is then inserted in the space as which is filled up with this material, and the height of which is such that when the pressure exerted upon the powder has attained a certain predetermined value, the material therein has been pressed to a square cross section. The pressing together of the flufi'y particles is efl ected by means of a member a acting like a plunger and arranged to be pressed vertic. ly into the space a: by means of a hydraulic press, which is continuously operated without stopping, while the member 72. is moved downward. When the valve of the hydraulic press is open in order to remove the pressure therein, the nut z is loosened by means of a key, while the nut j is tightened, whereby the wedge shaped locking device g is moved in the direction of the arrowo to open the press form. Simultaneouslywith the release of the pressure of the plunger member n upon the bar, the pressure upon the plates and (Z is also released, and the pressed bar can expand upward and laterally simultaneously with its expansion in a longitudinal direction, the latter expansion amounting to about 3 to 4 millimeters, and causing the plates 6 and f to move endwise, these plates being free to perform such movement. After the opening of the press form as above described, the bar can easily be removed therefrom.

The fact that the bars obtained from fiufiy material, according to the present invention, show a very great contraction (as far as per cent.) when they are fused at white heat, renders it possible to use the improved process for the manufacture of fused bars of great length, for instanceof 40 to 50 centimeters, and of small cross section, for instance-2 square millimeters, in order that when it is desired to simplify the working process these bars should be directly'subjected to the drawing process, without being first mechanically treated. I have found that the bars, the drawing operation upon which is started at a diameter of 2 millimeters, possess a much more and better fibrous structure ,in the case of thick wires, and are therefore more elastic than wires which are hammered down to one square millimeter, and. are then subjected to the drawing process.

Bars of rectangular cross section give rise to certain inconveniences when they are further treated, and in order to avoid these inconveniences the edges of the bar are generally ground by means of emery disks, an operation which is long and troublesome,

and which often causes the bars to break. Bars, however, obtained from pressed flufiy powder according to the present invention mering.

Although this press'mold has been described in special connection with metallic tungsten powder, it is not limited in this respect, since it is obviously suitable for the .manufacture of pressed bars from other finely divided metallic powders, especially those of the platinum group.

I claim:

A press mold comprising a rigid bed member having therein a long and narrow tapered mold recess wider at one end than the other, a rigidlining plate at the bottom of said recess, two lateral lining plates in said re cess, spacing elements for spacing said lateral-lining plates, a tapered wedge member cooperating with said tapered recess to clamp said lateral plates, a plunger operating between said lateral lining plates, and means for releasing said tapered wedge member to release the lateral pressure in the mold chamber.- p

In testimony whereof I have affixed my signature, in presence of two witnesses.

- KARL GLADITZ.

Witnesses:

M. BA KER, G. BERTSCH. 

